1. Field of the Invention
This invention relates generally to vertical displacement limit stops in a disk drive and more particularly to vertical displacement limit stops or crash stops, as opposed to actuator limit stops, for preventing impact between a disk surface and a work function member, such as the arm of an armstack, or an air vane, projecting between adjacent disks.
2. Description of the Prior Art
Prior art limit stops or crash stops in disk memory drives have addressed the problem of providing mechanical limits to actuator arm travel in moving armstacks of magnetic heads across tracks of magnetic recordings in magnetic memory disks. Other prior art, has addressed the problem of locking the actuator arm in a predetermined position with respect to the magnetic memory disks, with the magnetic heads positioned at a location on the disk surface where there are no recorded tracks.
The actuator arm lock is particularly useful in instances when the disk drive is being moved, as in shipping or handling, where the disk drive is subject to shock. The heads on the armstack of a free moving actuator arm can damage a disk surface as they sweep across the tracks in an uncontrolled manner. Destructive acceleration forces can also be imposed upon the armstack and the limit stops of the actuator arm if the actuator arm is not restrained or locked.
Efforts to meet the need for increased data storage in limited or reduced space in disk drives, have resulted in designs in which the axial spacing of the memory disks is being reduced. There are physical limits to size reductions in magnetic heads while still retaining functional utility and reliability. There are also physical limits to size reductions in the arms of armstacks which carry the magnetic heads and in their attachment points, while still maintaining the arm strength and stability required to properly move and position the heads. The result is that clearance between the armstack structure projecting between the adjacent disks is reduced. When the actuator arm is locked as in shipping, shock forces having force components paralleling the rotational axis of the disk, can cause relative movement between the disk stack and the armstack, in a direction substantially perpendicular to a disk surface producing impact between the armstack structure and a confronting surface of a disk. This can produce serious disk surface damage and data loss. Even if the data loss can be tolerated, the disk drive will be useless because during disk rotation the flying heads will not clear projections from the damaged disk surface. Destruction of the disk drive will likely result in this circumstance if use is attempted.
Presently known prior art neither addresses this problem nor suggests or provides a solution to this problem.